Gastrointestinal bleeding is often intermittent and its souree may be difficult to locate, resulting in delay of definitve diagnosis. Melena usually denotes bleeding not only from the upper, and lower gastrointestine but from the small int estine. Adult Meckel's diverticulum with gastrointestinal beeding is a relatively rare disease and often presents difficulty in preoperative diagnosis. A 65-year-old man was admitted to our hospital due to melena. Upper and lower gastrointestional endoscopy revealed no bleeding stie. (99m)Tc-pertechnetate scintigraphy is well known as a useful tool for preoperative delineation of Meckel's diverticulm. (99m)Tc-pertechnetate scintigraphy was performed in this patient and succesfully depicted the lesion noninvasively. In surgery, Meckel's diverticulum was found at an oral stie 90 cm from the terminalileum, and a sleevereseection was performed. Histopathologically, the diver ticulum had ectopic gastric muco sa and two 5mm ulcers on the border of the gastric mucosa.